Advances in solid state electronics over the last half-century have been predicated predominantly on improvements to and specialization of p-n junction based devices. Such improvements have been aimed at every aspect of device performance, from increased efficiency and yield to optimized frequency response, minimized noise, and more. Common p-n junction based devices include diodes, transistors, triodes, LED's (including OLED's), etc. Such p-n junction based devices form the core of the modern electronics industry.
However, the elemental p-n junction has some fundamental and unavoidable drawbacks, some of which stem from the physical p-n junction itself. For example, the p-n junction requires the extrinsic doping of intrinsically electrically neutral semiconductor material with positive or negative ions to create the respective p- or n-type materials forming the junction. Such doping is expensive, can damage the semiconductor lattice, and increases scattering centers that can decrease carrier mobility and increase resistance. Further drawbacks of traditional p-n junction devices owe to subtleties in the physical motions of carriers within the junction, p-n band structure, and more, leading to various problems in creating exceptionally high-conductivity, high current, high power, and high frequency devices. Finally, PN junctions may be limited by the solid solubility of their constituent materials.